1. Field of the Invention
The present invention relates to a method for forming an aerial metallic wiring in a fabricating process of a semiconductor typical in ULSIs.
2. Description of the Related Art
As a conventional technology relating to a method for forming an aerial metallic wiring, there is one, for instance, that is disclosed in Japanese Laid-open Application No. HEI 11-126820.
In this conventional method, an aerial wiring structure is formed in the following way. That is, a temporary film made of a carbon film is formed on a semiconductor substrate, a through-hole and a groove are formed in the temporary film, a Cu alloy film is deposited on the temporary film according to a sputtering method, the Cu alloy film is reflowed by heat-treating at a temperature in the range of 400 to 500 degree centigrade and filled in the groove and the through-hole, a plug for burying the through-hole and a wiring connected to the plug and extending onto the temporary film are formed (hereinafter referred to as “a reflow method”), thereafter the temporary film is burned and removed, and thereby an aerial wiring structure made of a Cu alloy is formed on semiconductor substrate.
In the conventional reflow method, since a bonding strength between the plug and the semiconductor substrate is deficient and the plug and the semiconductor substrate are likely to peel off, there are problems in that the aerial wiring may partially separate or an entirety thereof is likely to collapse.
Accordingly, the present invention intends to provide a method for forming an aerial metallic wiring in which a problem of bonding strength deficiency between the conventional plug and the semiconductor substrate is overcome, the bonding strength is improved, and an aerial wiring structure having excellent self-sustainability can be formed.